Evaluation location: Illinois, United States
In late August, after all adult beetle feeding had ceased, a field defoliation survey was conducted by visually examining the tree canopy from all four cardinal directions for each accession. Trees were rated by two independent estimators for evidence of feeding using a scale of 0-4 as follows: 0=no feeding, 1=very light feeding, 2=light feeding, 3=moderate feeding, and 4=heavy feeding. Depending on the availability of trees, three to five single tree replicates were evaluated per taxon.